Best DIY window insulation kit for draughty windows.
Updated: Jan 9
Can you eliminate window condensation with this £3.50 DIY window insulation kit?
In late December, I expected to be writing blogs about making mantles look pretty with foraged foliage and top tips on festive home fragrance but (yet again) 2022 threw us a curve ball with a post-pandemic cost of living crisis, extortionate energy bills and the Troll of Trondhein (what was that about??!). All this meant that I, like so many around the UK, was left sitting in a cold house, battling cold air and draughty windows, desperate to eliminate window condensation on the daily. So the magical mantles had to wait and I set about compiling tips and tricks to keep warm without the heating on (which you can read here) and combat condensation in the home.
We have central heating and if I let it do its thing, condensation wouldn't be an issue, well it certainly wouldn't be a big issue. But we aren't leaving the heating to do its thing because the utility bills would cost fifty million billion pounds a month. Instead, we (well, mainly me) are rationing the heating (Mr D sneaks it on at every opportunity in a fun cat-and-mouse style game of Thermostat Wars), resulting in an often chilly, and sometimes 'see your breath', freezing, house with condensation popping up on the inside of the window (s) every morning.
I researched the best way to reduce condensation in great detail and shared lots of my findings on my Instagram and Tiktok. It transpired, a dehumidifier is by far the most effective tool in the battle against condensation you can read my post about how to use a dehumidifier to stop window condensation here, but there are lots of small changes you can make to daily home life that also have a big impact. For example, draft stoppers, keeping lids on saucepans during cooking, shutting kitchen and bathroom doors and using extractor fans wherever possible. To tackle our bad loft condensation we installed some tile vents and they were a game changer.
Then, I stumbled across this bargain £3.50 DIY window insulation kit on Amazon (they are also available at your local hardware store) that promised reduced heat loss (& heating costs) as well as eliminating condensation in the cold weather, ideal for glass windows with cold drafts; I had to give them a try. Surely, this was too good to be true right??
How to use DIY window insulation kits
Here's the step-by-step process I followed to install the DIY window insulation kits that trap heat and prevent window condensation.
You will need Window insulation kit - like this one from Amazon
Cleaning spray
Sponge
Hairdryer
1. Clean the window and frame
Before you fit the DIY window insulation kit, you need to clean the window frame to ensure that the adhesive tape sticks around the entire window. This is also an important step because you don't want to spot any dirt on the windows after you've gone to the effort of sealing them up and making the gap completely airtight.
2. Prepare the window film
The plastic shrink film comes in large sheets that you need to cut to size, handy for larger windows.
With a measuring tape, measure the size of the window you are covering allowing a few cm extra on each side to reach the frames (where it will be attached).
Once you have the measurements (add a couple of cm to be safe as you can always cut if off but you can't stick it back on), cut the plastic sheet for a perfect fit so it's easier to handle.
3. Tape up the frames
Before you start this step, make sure the window and frames are fully dry, give them a wipe over to be sure.
Embarrassingly, I messed this bit up the first time...I had a bit of a blonde moment (!) and thought it was a good idea to position the double-sided tape for the DIY window insulation on the frames as close to the glass panes as possible (don't say it!) see the first picture.
Luckily, I realised before I'd stuck too much tape down that this defeats the whole point of the interior window insulation kit as you are aiming to trap a thick layer of air between the window pane and the film for best insulation, so for better results and a cozy room, you want to tape to the outer edge of the frame to achieve this. See the second picture for better tape placement. Apply the tape from the top of the window to the bottom of your window and peel the backing off once you are happy with the placement.
For best results, press the tape down firmly and then remove the plastic backing to reveal the sticky side
4. Apply the film
Working from a top corner, attach the plastic window film to the mounting tape.
Press firmly and stretch out the film as you go so it's taut.
Work your way down the window until the film is covering the whole pane and there are no gaps between the film and the tape, therefore making it airtight.
Use a hairdryer to apply heat to the edges of the film. Don't hold the hairdryer to close or in one spot for too long or the film will get too hot.
You should see the film tighten over the window, trapping a layer of air.
Effectively making the window double or triple-glazed, depending on what you started with.
5. Finishing touches
Once the film is attached to the window and is airtight, you can neaten up the edges by cutting off any excess film. This will make the film less obvious on the window. If any sagging occurs or wrinkles appear, grab the hair dryer again and spend a minute or two reapplying heat to shrink the film back again.
DIY Window Insulation Kit: The results
The key takeaway is that I was so impressed with how well they worked. The reduction in heat loss through the old windows was noticeable and there was no condensation on the glass, even in the mornings after the heating had been off all night. This was definitely one of the cheapest methods battle against heat loss in cold season.
The science bit
As air temp decreases, so does the volume of moisture it can hold (a room at 20c can hold twice the amount of water vapour that a room at 10c can).
- The dew point is the temp at which water vapour condenses into water.
- When warm moist air hits a cold (below the dew point) surface it causes condensation.
Conclusion ⬇️
- These kits are great for reducing heat loss through inefficient windows which will help save money on your heating bills, increase the room temp and stop the windows attracting condensation but won’t eliminate air moisture completely.
Therefore if your house is inadequately heated you’ll likely have other surfaces below the dew point (external walls for example) which will continue to attract condensation - so if you suffer with very bad condensation and can’t afford to keep a low level heat on all the time or improve the ventilation (retrofitting trickle vents / installing extractors fans etc) then I recommend using with a dehumidifier.
In short, for £3.50 these plastic film insulation kits are great value and will definitely help get better results for older windows and make a huge difference for single-pane windows, but won’t solve all your condensation problems without a dehumidifier as well.
A note about Trickle Vents.
Trickle vents are fitted to the window frame & allow humid air to escape and be replaced by clean air from outside. If your windows have trickle vents then I wouldn't recommend covering over them with window insulation kits as they do an important job ventilating rooms. Trickle vents could be an indication that your window is newer, already double glazed and therefore might not see a huge benefit from an insulation kit anyway, although that is a bit of a generalisation and each window should obviously be treated on an individual basis.
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New regulations came into force in the UK in June mandating that the windows in new builds & extensions have trickle vents fitted as standard unless they are exempt eg some listed or historic buildings & conservation areas.
Replacement windows only have to have them by law if the window you are replacing had them. It’s worth noting that you can retro fit them, without incurring the expense of replacing the whole window frame
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Condensation is rife in homes with poor ventilation and lack of airflow is often exacerbated by the measures people have taken to make their homes more energy efficient eg new windows and increased loft insulation. This year, we have the added issue of increased humidity in colder (often damp) houses from lack of adequate heating.
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Do you have trickle vents? Did you know that you should leave them open all year round?
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Common misconceptions mean people worry they cause draughts but they don’t due to their design. They will reduce energy efficiency very slightly, but the benefits from improved air quality and reduced condensation are definitely worth it.
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